Interested by the comments on riding skills, etc. I was passed twice by large pelotons and I can understand why riders want to take advantage of the closed roads - the big groups certainly didn't cause me a problem and when I saw them coming the opposite way they seemed to have plenty of open road ahead of them. I was also passed many times by groups of 10-12, jumped on the back of one or two, and these seemed quite well organised.
I think we need to remember this event attracts mixed abilities from those on mountain bikes, who I felt very sorry for as the vast majority whizzed by them, up to some very serious riders. The riders I did have a problem with were in groups of 1-3 desperate to push through, several times I had other riders push through very small gaps at speed a bike's length ahead of me - a bit like those people who constantly jump lanes on a motorway. On one u-turn a guy came inside me, even though I had gone wide, took my line forcing me to brake hard and feel the back wheel wobble for the first time in years!! Daft manouevre.
I like to think I'm a decent club rider with experience of group riding and also know how to ride in yesterday's event. It seemed to me the guys riding at around 21-23mph pushing through people should have been using their experience to know when to back off and wait or to plan their move much further ahead rather than just diving in. Afterall we were all trying to have fun on the same bit of tarmac.
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Due to riding almost exclusively in the draft of the first or second group I finished with a time of 2:08, over 5mph faster than I did the 26 last year on my own! I can't speak about other groups but most passes were very clean with shouts of "stay left" ect, the only slight problems were when the road was suddenly narrowed by cones. I think the very front even had a motorbike ahead of them! I think it was clear most of the riders were club riders and wheels were rarely overlapped. I also only saw about one pair of tribars in the first 40 riders (guy with ironman tattoo who never seemed to use them), I also can't remember any deep rim wheels which I saw quite a few of in later groups.
The front of the group did slow before passing, but I think for me and most of the riders behind slowing down and leaving a 10m gap would mean there would be no way back on.